A light unit uniformly illuminates a rear side of a Liquid Crystal Display (LCD), which is not self-luminous, in order to show a display image. A light guide plate is included in the light unit to provide uniform illumination and brightness, which may be a plastic lens that uniformly transmits light, emitted by a light source (e.g., an LED), to the entire surface of the LCD.
FIG. 1 illustrates a structure of a light unit using an LED as a light source. As illustrated in FIG. 1, a plurality of LEDs 20 are provided on a printed circuit board (PCB) 10, and a light guide plate 30 is provided to transmit light, emitted by the LEDs 20, to the top of the light unit. Recently, continuous attempts are made to use LEDs as a light source to perform a uniform surface light emission on the entire light emission surface. In this case, a plurality of LEDs are arranged on a plane surface, and are inserted into concave holes formed at a light guide plate.
However, if an LED is inserted into a light guide plate, a hot spot X occurs due to heat at a surface near to the LED. This hot spot X relatively increases the brightness in a region near to the LED, causing a brightness spot.
Also, the high-temperature heat or thermal shock occurring at the LED causes the thermal expansion of a light guide plate, a reflection film and a PCB. In this case, the LED is damaged by the difference between the thermal expansion rates of the respective components.